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干旱区地理 ›› 2018, Vol. 41 ›› Issue (3): 528-535.

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Holocene temperature changes in arid Central Asia revealed by GDGTs of loesspaleosol sequence in Tianshan Mountains

DUAN Yan-wu1, SUN Qing2, XIE Man-man2, HOU Ju-zhi3, LIANG Jie3, LI Guo-qiang1, CHEN Fa-hu1   

  1. 1 Key Laboratory of Western China's Environmental Systems(Ministry of Education), College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000, Gansu, China;
    2 National Research Center of Geoanalysis, Beijing 100037, China;
    3 Institute of Tibetan Plateau Research, Chinese Academy of Science, Beijing 100085, China
  • Received:2017-11-29 Revised:2018-03-12 Online:2018-05-25

Abstract: The study of temperature changes during Holocene plays an important role in understanding current global warming and forecasting temperature changes in the future. However, the temperature change trend during Holocene inferred from proxy index reconstructions are contradicted with those from climate model stimulation. In this study, four samples from a loess-paleosol sequence(LJW10) in Tianshan Mountains, arid Central Asia, were used to reconstruct annual temperature trend during Holocene. The proxy index of MBT'5ME and transfer function derived from GDGTs of those samples using newly proposed analytical approach were used for temperature reconstruction. As a result, we achieved separation of 6-methyl br-GDGTs using improved chromatography, the temperature inferred from MBT'5ME index of the four samples was -6.3℃,1.9℃,4.3℃ and 6.6℃ respectively at the corresponding depth of 2.2 m, 1.6 m,1.2 m and 0.6 m. The reconstructed temperature at the depth of 0.6 m was in accordance with the modern meteorological record, which indicated our temperature reconstruction is reliable. Importantly, we find the low temperature phenomenon in mid-Holocene and the gradual temperature increasing trend since Holocene, which are consistent with results from the climatic modeling. It helps understand Holocene temperature conundrum induced by the records and the climate model. However, there is a significant difference on temperature trend during Holocene between our results and the results based on brGDGTs using Chinese Loess Plateau(CLP). This may be due to different distribution of seasonal rainfall, which caused the temperature recorded by br-GDGTs was about summer in CLP but annual average temperature in Tianshan Mountains. The seasonal response of br-GDGTs to temperature still can not be ignored. It should be also noted that this study is only a preliminary step in the research of using GDGTs and MBT'5ME index to reconstruct the temperature change in Holocene and the next step is to continue with this model using higher temporal resolution.

Key words: Loess, br-GDGTs, Holocene, temperature reconstruction

CLC Number: 

  • P534.63.2